Tom Swift and his Sonic Boom Trap

By Victor Appleton II


A weird blast of sound engulfs an American city. Tom is caught in the panic while visiting there to demonstrate his new sonic boom deadener--the Silentenna--at a Noise Reduction Conference. A top-rank scientist, John Wyvern, who is also attending the conference, mysteriously vanishes the day of the sonic attack.

Attempts on the lives of both Tom and Wyvern's pretty daughter intensify the young inventor's determination to solve the mystery. A clue to John Wyvern's whereabouts takes Tom to the sun-scorched Australian Outback, where he uses his latest invention-- robot bloodhound--to track down the missing scientist, but a deadly bush fire wipes out the trail.

Meanwhile, other cities in the United States have suffered terrifying eruptions of sound. The President receives an unsigned ultimatum, threatening an all-out sonic blitz unless the blackmailer's price of ten million dollars is paid.

Tom's Silentenna offers the only hope of defense--but to perfect it he needs a special liquid-crystal device which only the missing scientist can supply. The young inventor's race against time to thwart the unknown sonic enemy will keep every reader's pulse pounding with excitement and suspense.


A more detailed summary of this book is in preparation! Stay tuned÷




Major Inventions


There are two important inventions in this book: the Silentenna and F.I.D.O. Since the amazing Silentenna is more important and more incredible, I'll discuss it first.

The Silentenna is Tom's attempt to build a machine that can cancel out sound. The idea behind it is simple: the machine detects sounds, analyzes their wave pattern and then beams out a sound wave that is exactly out of phase with the wave it detected. These two waves would cancel themselves out, producing silence.

The reason Tom was developing a Silentenna was to solve the sonic boom problem. As is generally known, when a plane exceeds the speed of sound it creates a sonic shockwave that trails behind the plane. This shockwave is very dangerous: not only is it loud and annoying, it also has the ability to shatter windows, ruin crops, and in general cause widespread damage. This is one of the reasons why supersonic airliners do not sail the skies as futurists once predicted: no one wants an airplane that pulverizes the country it is flying over, so supersonic flight has largely been relegated to oceanic crossings. If someone could develop a way to cancel out or remove the shockwave the last hurdle to supersonic flight would be solved -- and that is exactly what Tom Swift hoped to do.


How does the Silentenna work? Simple sound cancellation: the sound the Silentenna emits is exactly out of phase with the sounds it detects. As Tom Swift put it:

"You see, this transducer on top of the Silentenna emits sounds of equal frequency and volume to any sounds which the device 'hears,'" said Tom. "But the output sound waves are exactly out of phase with the input, so the incoming sounds--in this case, Bud's whistle--are canceled out."

This is a well-established fact; airplanes use this method to reduce engine noise, and I have heard that some construction sites have implemented this sort of system to keep noise down to a manageable level. The problem, however, is that this method can't get the complete silence Tom was able to achieve÷


How well did Tom's Silentenna work? Tom built several models of his Silentenna. The first model (Mark I) worked perfectly but only at a short range. In the first chapter there is a beautiful scene when Tom uses the Silentenna to play a joke on Chow. Chow had been annoyed with the robotic dog Tom built; when FIDO got in his way Chow tried to kick it -- but FIDO eluded him and Chow hit the ground, hard. Chow heard Bud laughing in the background and wasn't pleased:

"Oh-oh! Plug your ears!" Bud said. "We're about to get blasted!"

"Quick! Inside!" Tom hissed. "I just had an idea!"

He darted to the center of the room as Bud slammed the door. An usual-looking electronic device was mounted on the workbench. Tom barely had time to flick it on before Chow Winkler came stumping into the laboratory.

"Brand my pothooks, boss!" he stormed. "If that hydrophobiated mechanical polecat don't--"

Suddenly Chow's voice was cut off. His mouth continued moving and his jaws worked vigorously, but not a sound came from his throat!

The cook's eyes widened with panic as he tried again and again to shout at the boys. But the silence in the lab remained unbroken. Chow began to gesture frantically and clutch his neck.

Clicking a knob on the electronic device, Tom said calmly, "What's the matter, Chow? Don't be bashful. If there's something you want to tell us, please say it right out." The young inventor kept a straight face, but his eyes were twinkling.

Tom (who seems to be in a playful mood in this book!) plays the same trick later on a loudmouth know-it-all science-fiction writer who later tours his plant as part of a group of reporters. The problem, however, is that this scene isn't possible: while a Silentenna can reduce sound, it can't completely eliminate a series of sounds as complicated as a voice. Sound waves travel at a finite speed, and even at electron speeds it isn't possible to analyze a series of sounds like that quick enough and generate a countersound in time to create complete silence. There's more to it than that; but to sum it all up: it can't be done.

Of course, Tom's goal was not to create a way to silence the loudmouths of the world (although this does seem like a noble goal! Perhaps one of these should be instituted in the halls of Congress and used now and then at appropriate moments.) Tom wanted to cancel out sonic booms: was his invention a success doing that?

Actually, no, it was not. In Chapter II Tom Swift had his Mark II Silentenna installed on a plane (although he designed it for mounting under the wings of the Sky Queen). Tom held a public news conference to watch the testing, and in front of a crowd of reporters and officials Bud flew the plane, broke the sound barrier -- and created a sonic boom. Tom was heartbroken: his device helped muffle the sonic shockwave, but it didn't cancel it out.

Tom was confident, however, that he had the right principle. The Mark II worked a little differently than the Mark I:

"As you know, sound waves are transmitted through air by to-and-fro vibration of the air molecules."

Bud nodded. "That much I savvy."

"Well, my Mark II damps out their vibration by pulsing out a repelling force at the same frequency. IT's as if you were to slow down and stop a playground swing by pushing against it every time it swung toward you."

"Sounds great!" said Bud. "How about that snaky coil of tubing?"

"That's the power tube which generates the pulses," Tom replied. "And those long slots are sample intakes, through which the Silentenna finds out the direction and frequency of the sound waves."

Tom did not give up. Working closely with his Dad, he isolated the problem (a faulty crystal) and produced a new prototype. Instead of retesting its effectiveness in sonic booms, though, he instead used it to battle the sonic invaders÷


What about the sonic brainwashers? This is one of the few books in the Tom Swift series that does not pit Tom against Brungarians, Kranjovians or hostile forces from Outer Space. No, this time Tom is pitted against two enemies: one group who wants to blackmail the U.S. Government out of millions of dollars, and another group that is brainwashing brilliant scientists and high government officials. The brainwashing scheme is probably the darkest plot in the Tom Swift series. As the book explained:

Delperta confessed that he and his brother had masterminded a worldwide kidnap ring which specialized in seizing top scientists and government officials. The victims were flown to a small jungle island off the Australian coast and then smuggled into the Territory by his brother. Here they were brainwashed to extract their secrets by techniques which the Delpertas had learned in a totalitarian country. The secrets were sold to foreign powers or unscrupulous industrial firms. Then the victims were returned home with all memory of what had happened blanked out.

"We did them no harm," Delperta defended himself.

"Aside from the mind-warping you inflicted on them!" Tom snapped back in a cold, angry voice.

Tom wasn't kidding. Tom stumbled upon the brainwashers when they kidnapped John Wyvern -- a scientist whose knowledge Tom desperately needed to defeat the blackmailers. Here is what Wyvern was like before the kidnapping:

÷One was John Wyvern, a top-rank crystallographer from the Sonicon Research Institute.

"That's exciting work you're doing, John, on obtaining a piezoelectric effect from supersmectic liquid crystals," Mr. Swift said as they shook hands. "I hope we'll hear more about it at these meetings."

"You will, indeed. I'm reading a paper on my latest experiments at the morning session tomorrow." Wyvern hastily introduced÷

When Tom finally tracked down Wyvern again he was in sad shape:

As they entered, they saw the sandy-haired scientist lying cringingly on his cot. He was cleanly clothed and shaven, but his eyes were as full of fear as ever. He replied only in low mumbles when Tom and the sergeant tried to talk to him.

Earlier in the book when Tom found him in the Australian outback he was in even worse shape: he couldn't talk, he was completely out of his mind and he acted like an animal. The techniques the sonic brainwashers used were very effective: they had reduced Wyvern to little more than a vegetable. At the end of the book Tom and Bud themselves got a taste of the brainwashing treatment. It was crude but effective: simply blast very loud, raw sound at someone long enough and they will go insane. Would that really work? I don't know, but I sure don't want to find out! I suspect it would÷


What about the sonic attackers? Tom faced another enemy besides the sonic brainwashers. Early in the book, Tom flew to Detroit to attend a scientific conference. While he was there the city was hit with a sonic attack:

Suddenly a shrill blast of sound split the air÷the noise grew louder and louder until the explosion of sound was almost skull-bursting! Many cars pulled over to the curb÷

The blasting sound began to rise and fall crazily in pitch. Pedestrians scurried into buildings and doorways, clutching their ears÷

÷A faintly audible crash outside drew their attention to the street. Two speeding cars had just sideswiped each other.

Brakes screeched and another crash could be heard as cars began to jam up behind the two vehicles. Horns honked vainly above the din÷

The taxi driver turned a frightened face to the boys and yelled, "Don't panic, e says! Whadda we supposed to do? Plug our ears and go nuts?"

Bud grinned wryly. His own face was looking strained. Even with the taxi windows closed, the din was deafening. Both boys' heads were throbbing from the torrent of sound, and the weird undulations in pitch made it even more nerve-racking.

Pedestrains were running for cover in evident terror. A bulging-eyed woman opened her mouth in an unheard scream, then collapsed on the sidewalk. A man helped her to her feet, then into a store.

÷news flashes over the radio reported numerous traffic accidents and cases of people who had collapsed during the eruption of sound÷

÷several suffered brain damage. Two others almost died from shock reaction÷

Speculations abounded. Soon San Francisco was hit with a sonic attack, and then Atlanta. The country was thrown into turmoil and fear; what was behind these attacks? Tom soon found out: he was summoned to the Pentagon and found out that:

"An unsigned letter to the President was received in this morning's mail," Frome [Assistant Secretary of Defense] went on. "I'll read you its contents."

He paused to pick up a typewritten paper.

"Sir: You have already seen--in Detroit, San Francisco, and Atlanta--what can happen to a city under sonic attack. Any city, from coast to coast, is just as vulnerable.

"But the three attacks so far have been only a sample--mere fleabites. Under a prolonged, all-out sonic blitz, a city could be reduced to utter chaos, with all traffic and communications disrupted, and thousands dead or hospitalized.

"We have no wish to carry out such an attack. But the choice is yours, Mr. President. You can prevent it by the payment of ten million dollars÷

So Tom's mission became clear: could he use his Silentenna to defend against the sonic attack? Tom decided to try; he was his country's only hope. At first Tom pinned his hopes on finding John Wyvern, for Wyvern was the only man who could build the crystals Tom needed for his Silentenna. When Wyvern was at last located and found to be a mental vegetable, though, that hope was dashed to pieces. Tom, for all intents and purposes, had failed!

This is unheard-of in the Tom Swift series: normally Tom would stay up late a few nights, eat some of Chow's sandwiches and (with a few mishaps and after being knocked out a few times) come up with the answer. After 26 volumes, however, Tom's luck had finally run dry: his invention failed and Wyvern -- the world expert that Tom needed -- had been brainwashed into insanity.

Tom was rescued by an inventor as great as he was: namely, his father, Tom Swift Sr. His father had starred in a 40 volume series of his own; throughout his career he had cranked out one marvel after another: electric trains, war tanks, giant magnets, ocean airports, electric rifles, and many more. Some of Tom Sr.'s inventions saved Tom Jr.'s day: his giant magnet, for example, rescued Tom's Jetmarine from the ocean floor. Tom Jr. might have taken the stage, but Tom Sr. had lost none of his brilliance.

As Tom Sr. explained it, the activator was a simple matter:

Mr. Swift reached into the pocket of his tweed jacket. "I think our problem's solved."

The scientist pulled out a small device made of a glistening white material. It was approximately cylindrical with irregular outer walls and wire leads at each end. An intricate lengthwise coil arrangement was connected to the cylinder by a pair of metal collars.

"Made of Durastress, isn't it?" Tom queried. This was a plastic of amazing strength which he had invented to encase the midget atomic power plant in his flying atomicars.

"Yes, and it never came in handier. I discovered how to cast it to a ten-thousandth tolerance with the liquid crystals frozen inside. Using the Durastress completely eliminated any machining or polishing."

Mr. Swift said he had worked all night before finding a solution. "Varying the potential over the coil changes the size of the crystal, causing it to slide right and left over a central tube--thus varying the frequency."

"Dad, this is terrific! I'll bet it's superior to Wyvern's model!"

"Hank Sterling has a crew turning out a whole batch of these," Mr. Swift added.

Tom was thrilled. He changed his Silentenna to work with the new crystals and then tested them out; they worked perfectly. Armed with the new device, the President turned down the blackmailers. They retaliated by attacking New York City at the height of rush hour traffic. Tom's device saved the day: it reduced the sound to a bearable level, and he traced the sound to its source -- little flying devices he called screaming meemies.

For those who are curious, the New York attack in Chapter 19 is the cover scene for this book. The cover shows the Sky Queen, armed with dual Silentennas, canceling out the sonic blitz. New York is shown in the background with the Hudson River in sight (and could that tall black building be the Empire State Building?) The little red whirlybirds that dot the cover are the screaming meemies -- 14 of them, which is an unfortunate error. As a matter of fact, the enemy only had a handful -- and they were very careful to keep them out of sight. Still, the cover makes for an exciting scene! With a cover and title like that, what Tom Swift fan wouldn't be interested in the book??


What do we know about the screaming meemies? The sound in the blitzes was generated by little devices Bud christened the 'screaming meemies.' The devices were pretty clever: if the sound generators were located in one spot someone might locate them, so they mounted them on little helicopters and flew them all around the city. A moving sound generator is a lot harder to find than one mounted in one place, and before it could be found the attacks were cut short and the devices flown back home.

Tom didn't know about the meemies until after he had silenced the attack on New York. Hank Sterling was the first to spot one:

"We've spotted one of the sound emitters!"

"What's it like?" Tom asked breathlessly.

"Small--about the size of a grapefruit. Three little rotors. It's flying like a copter÷I'm going to ram it, skipper!"


"Man alive! This thing is really a masterpiece of miniaturization! It even has a small, built-in radar to avoid obstacles."

"It was radio-controlled, eh?" Bud asked.

"Right." Tom traced the guidance and steering systems. "I'll bet this packs enough power to stay airborne for more than a day."

As he probed into the small but tremendously powerful sound generator, Tom's jaw dropped open in a look of utter astonishment.

"What's strong, skipper?" Hank inquired.

"It has a liquid-crystal activator!"

"Like John Wyvern was working on?"

"It could be the same as Wyvern's," Tom said. "They may have forced more data out of him by brainwashing than Delperta let on. Anyhow, this sure explains why they wanted his technical know-how! They needed a flock of these for their flying sound emitters."

If you ask me, the screaming meemies are far more amazing than they let on. An airplane the size of a grapefruit that can stay airborne for a day is a tremendous accomplishment -- it's simply not possible with today's technology. I imagine the Air Force would give a lot to have one of these: not only could they stay airborne but they had radar guidance systems, were remote controlled, and autonomous. And to think they could generate a sound loud enough to destroy a whole city! Clearly, these were some of the most brilliant enemies Tom ever faced. Perhaps such a feat will be visible a few hundred years from now, but not today÷


How feasible is it to build a Silentenna? As I said earlier, the Silentenna already exists in many forms; airlines use them to make air travel more comfortable. Sound reduction is a useful technology; I imagine that it is used in all sorts of places. However, what Tom Swift had in mind was not sound reduction but sound elimination -- and that is a whole other field altogether. I am no expert in the field of sound, but I imagine Tom's invention was a little harder to build than he let on. Complete sound cancellation would probably require a radically different technique altogether; I'm not at all sure it's even possible. I also have my doubts as to the usage of a Silentenna to eliminate sonic booms: that sounds so simplistic an answer that I think if it was as simple as that it would already have been done.

A much more realistic device is the Screaming Suzie in the Rick Brant book THE WHISPERING BOX MYSTERY. In that book, a group of criminals had built a device (a 'whispering box') that generated a certain frequency of ultrasonic sounds which knocked people out. The gang at Spindrift was given the assignment of creating a defense against that sort of weapon, and so they created the Screaming Suzie. Suzie worked along the same principles of the Silentenna: it detected a sound, analyzed it, and generated a countersound that canceled it out. The reason the device was called Screaming Suzie was because the cancellation wasn't perfect: while it did render the 'whispering box' harmless, it didn't completely eliminate the sound: it simply decreased it into an earsplitting wail.


How much impact would a Silentenna have on civilization? Quite a lot, I would imagine. The purpose behind the Silentenna was to cancel out sonic booms and give planes a way to travel well in excess of Mach I without leaving behind a wake of destruction. If a way to cancel out or eliminate the sonic boom could be found, air travel could change dramatically: today's legion of subsonic planes could give way to supersonic jets capable of going Mach 2 or 3. Long cross-country flights would take only an hour or so; any point in the country could be brought within a mere hour's journey. The long 13 hour flight from New York to Tokyo (which I have flown many times and let me tell you something: it isn't any fun) could be cut to only a couple hours. Flight would be revolutionized: it could be that, someday, going across town would take longer than going across the country. (Isn't that an odd thought?)


Finally, I don't want to leave without saying a few words about FIDO! Chow hated this dog with a vengeance; he was always underfoot and giving him trouble. Tom built him as an experiment in thinking processes, and later he became a guard-dog: Tom modified him to protect Wyvern's daughter from the criminals who held her father captive. The dog had yet another usage as well: when Tom needed to track Wyvern in the Australian Outback, he put a modification of his aquatomic tracker equipment onto the dog and used him as a bloodhound to track the missing scientist.

Here's what the book has to say about the electronic mutt:

FIDO--named for Feedback Informational Deductive Organism--was a mobile adaptive machine which Tom had built to help shed light no the thinking and learning processes of living beings. It was powered by a thermionic device which converted heat directly into electricity. The automaton moved freely about the lab building, guided by infrared sensors, seeking sunshine and other sources of heat to "feed on."

÷The newsmen were intrigued with Fido, especially when they saw how the robot would dart hungrily toward the heat of a lighted match, like a dog responding to a dinner whistle.

Tom explained how Fido had 'learned' the best places in the building to probe for heat energy at different times of day. When his batteries were fully charged, the robot would 'sleep' or 'play' friskily about the corridors, but would start prowling hungrily when its supply of electricity began running low.

Tom doesn't claim to be the inventor of that kind of machine. Gull (filled with love for Tom, I am sure) pointed out that "Gray Walter's machines in England and 'the Beast' at the John Hopkins Applied Physics Lab are far more advanced and instructive." Tom, however, simply said that "÷I hope Fido may offer some new angles on memory and learning" -- and, perhaps, he did.

Tom Swift and his Polar-Ray Dynasphere | Tom Swift and his Subocean Geotron | Index

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